Additional information:

Western sand darter

Ammocrypta clara

What do they look like?

Ammocrypta clara is a small, very slender fish. Its average adult size ranges from 42-67mm (1.7-2.6in.). The word ammocrypta means "concealed in sand" and clara means "clear"-which is a reference to its clear or translucent flesh. As with almost all members of the family Percidae, the western sand darter has two dorsal fins. The first dorsal fin has 10-12 spines, and the second dorsal fin has 9-12 soft rays. The pectoral fins are fairly large and located directly behind the opercles; its pelvic fins are thoracic and located directly behind the head at the anterior end of the abdomen. Its fins range from clear to weakly pigmented along the spines and rays. Live specimens are very pallid-almost transparent. Preserved specimens are light tan or straw-colored. There is a row of twelve or more small dark saddles located down the center of the back. Along both sides of the fish are rows of 10-12 small oblong spots. The scales of the western sand darter are ctenoid. The breast and belly are completely devoid of scales; scales cover the dorsal surface from its median to the lateral line. The caudal peduncle is almost completely scaled. The caudal fin is slightly lobed (Becker 1983).

Until recently, the western sand darter was considered to be the same species as the eastern sand darter (Ammocrypta pellucida). The two species were separated based on scale counts, opercular structures and pigmentation. In contrast to the eastern form, the western sand darter has only 3-5 scale rows on the side of the body, a needlelike opercular spine and less pigmentation in the mid-dorsal and lateral blotches (Becker 1983).

For 47 western sand darters from central Wisconsin, the calculated lengths at the first three annuli were 43, 56 and 61 millimeters-almost identical to the calculated lengths for southern Wisconsin populations. The western sand darter reaches 71% of its total growth during its first year of life, and 91% during the second year. Females are generally larger and more numerous than males (Becker 1983).

What kind of habitat do they need?

The western sand darter is found in medium to large rivers that have moderate to swift currents, primarily over extensive areas of sandy substrate. It is generally found in water that ranges from about .2-.9 meters in depth. Water preference of the western sand darter is for clear to slightly turbid water (Becker 1983).

How do they reproduce?

Little is known about the spawning requirements or the reproductive behavior of the western sand darter. It has been suggested that spawning may occur in mid-summer, judging by increased activity then and gravid females (Lutterbie 1976). By examining the ovaries and development of breeding tubercules, Williams(1975) placed the height of the breeding season in July and early August. Williams found females with mature ova in late August. In Wisconsin, western sand darters spawn from late June through July (Lutterbie 1976).

How long do they live?

How do they behave?

One very interesting aspect of this fish's behavior is its habit of burying itself in the substrate (Daniels 1989). Several researchers have investigated this phenomenon in an attempt to explain its adaptive usefulness. Williams (1975) concluded that the sterile nature of the sand darter's habitat generally precludes the presence of predatory species. This absence of predators would suggest that the survival value of the burying behavior may not be due to the protection it provides; this behavior may be more important in energy conservation. For a fish to maintain its position in the moderate to fast current of a sand riffle, its energy expenditure would be considerably greater than if the same individual lied buryed in the sand. It is thought that the lower temperature below the surface of the sand results in a reduction of the metabolic rate (Becker 1983).

How do they communicate with each other?

What do they eat?

The few studies that have been performed indicate that major food items include small or immature aquatic insects such as mayflies (Ephemeroptera) and midge larvae (Diptera:Chironomidae)

(Lutterbie 1976).

Do they cause problems?

The western sand darter has no adverse affect on the human environment.

How do they interact with us?

There is little evidence that this species has a positive or negative benefit to humans. Because of its small, slender body it is not suitable as a bait fish (Becker 1983). However, the continued existence of this species will be directly influenced by humans. As has been stated elsewhere, the decline of the western sand darter has been directly linked to the degradation of aquatic habitats throughout the natural range of the sand darter-as the result of human activities. Perhaps the greatest benefit that Americans can derive from the western sand darter by its continued existence will be its contribution to the biodiversity of North America.

Are they endangered?

Reports from various agencies around the country indicate that the western sand darter is declining in abundance. Especially hard hit have been the populations in the central part of the range for the species. It is listed as rare in Illinois, depleted in Missouri, threatened in Iowa, and extirpated in Kansas. Wisconsin has placed the western sand darter in the Lake Michigan drainage on watch status. According to Cross (1967), fluctuating water levels and increasing siltation are especially detrimental to sand darters (Becker 1983). Stream degradation related to siltation is also cited as negatively impacting western sand darter populations (Page 1983).

Some more information...

There is unpublished evidence that this fish species has been found in an additional river-watershed in northern Wisconsin and Michigan. An entrainment mortality study was conducted for Wisconsin Public Service (WPS), on the Menominee River, as part of their relicensing requirements for the Federal Energy Regulatory Commission (FERC). This study took place between May 1993 and April 1994. During the summer of 1993, 28 discreet samples, collected on 17 different sampling dates produced 104 specimens of this species (WPS 1994). After verification of the identification, several specimens were donated to the University of Michigan Museum of Zoology. Their accession number is 224173(Personal comm).

Contributors

References

1994. Final Report for Fish Entrainment and Turbine Mortality Study at the Grand Rapids Hydroelectric Project (FERC NO. 2433) on the Menominee River May 1993 through April 1994 Prepared for Wisconsin Public Service Corporation(WPS) , Green Bay, Wisconsin. Bedford, New Hampshire: Normandeau Associates, Inc..

Lutterbie, G. August 1976. The Darters (Pisces: Percidae: Etheostomatinae) of Wisconsin. A Thesis submitted in partial fulfillment for the Degree of Master of Art in Teaching(Biology): 17-25; APPENDIX III.